The present invention relates to brewing beverages and more particularly to a method of and apparatus for brewing beverages in filter pouches. Even more particularly, the present invention relates to a method and apparatus for reducing brew water bypass of filter pouches and improving consistency of brewing within filter pouches.
Brewing coffee typically results in the extraction of 15% to 30% yield of dissolved solids from coffee particles, which are mixed with hot brew water for several minutes. A resulting fluid extract is gravity filtered from spent coffee grounds by a piece of filter paper. Commercial brewing machines provide about half a gallon of hot water, typically at about 195xc2x0 F. to a spray nozzle above a brew basket. In the brew basket is placed an open cup-shaped filter onto which is placed a quantity of flavor extractable coffee particles. When brew water is sprayed onto the loosely packed particles, the particles tend to float and many become suspended or fluidized in the brew water. This is believed to represent the ideal condition for brewing the maximum dissolved solids from the particles. Brew water is typically sprayed for about 3 minutes onto the particles where it continuously flushes extracted material from the particles as the fluid extract passes through the filter. The brew basket preferably has a discharge opening under the filter sufficient to drain all fluid extract from the filter in about 3 to 4 minutes.
A problem with the standard loose particle brewing system is that particle spillage and contamination are present at different points in the process. For example, particles may be spilled when manually dumping them into the cup-shaped filter. Also, particles may bypass the filter if brew water overflows the filter or the filter is otherwise placed improperly in the brew basket. Furthermore, each batch of spent grounds has to be removed and is often spilled when the wet filter is pulled from the brew basket for disposal. To solve the particle containment problem, the commercial brewing industry has adopted filter pouches of various designs, wherein a pre-measured quantity of loosely packed particles is totally enclosed within each pouch. The user therefore never handles particles directly.
Although filter pouches may solve one problem, they often cause other problems. For example, even though particles may be loosely packed within a filter pouch, insufficient space for particles to expand and become fluidized can result in the agglomeration of some particles. The agglomerated condition is much less conducive to extraction than is particle suspension. Lower percentages of dissolved solids are extracted when pouches have insufficient internal space. Prior art discloses pouches of complex and expensive construction which provide for pouch expansion in order to provide the required internal space.
Another pouch problem is that filter material located between the brew water spray and the pouch-contained particles may interfere with the fluidizing of particles. The brew water must first enter the pouch before particles may be fluidized for brewing. Although brew water easily passes through filter material, overall open area is often insufficient to allow the full flow of brew water into the pouch. If the pouch is not able to adopt a cup-shape to form a reservoir, some brew water may bypass the filter pouch, ultimately diluting the fluid extract from the pouch. Other pouch and brew basket designs intend for the pouch to form a fluid seal with the basket so that external bypass cannot occur. Such sealing is inconsistent, however. Furthermore, when a filter pouch is partially filled with particles in order to permit particle expansion, manual handling of the pouch may result in most of the particles accumulating at one end of the pouch. If this is not corrected when the pouch is manually laid horizontally in the brew basket, a portion of the pouch will likely be empty. Brew water easily finds such empty portions and flows directly through the pouch without contacting particles. This too is an undesirable form of brew water bypass.
What is needed is a filter pouch brewing system which reduces undesirable brew water bypass and yet provides sufficient space for particles to become suspended in brew water inside the pouch for consistently optimum brewing.
In practicing the present invention the problems of particle containment, brew water bypass, and providing space within the pouch for particles to expand without agglomerating are solved, so that consistent and optimum brewing is possible with each replacement filter pouch used in a brewing system.
In one preferred embodiment of the present invention, a method of brewing a fluid extract uses a filter pouch containing flavor extractable particles. The method includes a step of supporting a fully compliant, fluid-permeable filter pouch partially filled with flavor extractable particles such that the pouch is inclined at an angle to horizontal ranging from about 30xc2x0 to about 90xc2x0 so that the particles accumulate at a bottom end of the filter pouch. Another step is directing brew water to near an upper end of the filter pouch above the particles. The brew water enters the filter pouch without the need for an opening in the filter pouch. The brew water drops to infiltrate the particles.
The particles are partially fluidized by and suspended in the brew water and they rise with the brew water into an empty portion of the filter pouch without a need for opposing sides of the filter pouch to separate to generate internal space. A further step includes brewing a fluid extract from the particles in the filter pouch and discharging the fluid extract from the filter pouch. The filter pouch has sufficient exit area that a fluid extract discharge rate matches a rate of brew water entry into the filter pouch when a fluid head is produced inside the filter pouch which is at least as great as a vertical depth of particles in the filter pouch.
The filter pouch is preferably supported in a brew basket by a fluid-permeable support member. The method further comprises the step of draining the fluid extract from the brew basket at a rate sufficient to prevent a pool of fluid extract contacting the bottom end of the filter pouch so that the fluid extract discharge rate remains substantially undisturbed.
The step of directing brew water to near an upper end of the filter pouch is preferably accomplished by using a brew water conduit in contact with an outer surface of the filter pouch to reduce surface tension thereat as brew water flows over or through the conduit, such that the brew water enters the filter pouch with minimal resistance, thereby reducing brew water running off the outer surface of the filter pouch. The brew water conduit is preferably a plurality of flexible fingers in fluid communication with a brew water reservoir having drain holes. The flexible fingers contact the outer surface of the filter pouch as brew water flows over the fingers from the drain holes.
In another preferred embodiment of the present invention, a replaceable filter pouch and reusable brew basket apparatus for a brewing system includes a fully compliant, fluid-permeable filter pouch. The filter pouch is partially filled with flavor extractable particles. Also included is a brew basket having a fluid-permeable support member therein. The support member supporting the filter pouch is at an angle to horizontal ranging from about 30xc2x0 to about 60xc2x0. The support member locates a bottom end of the filter pouch sufficiently above a bottom surface of the brew basket to avoid contact with a fluid extract pool at the bottom of the brew basket during brewing. Further included is a means for directing hot brew water from a reservoir to near an upper end of the filter pouch for entry into the filter pouch above a level of particles therein, so that brew water infiltrates the particles to brew a fluid extract therefrom. The fluid extract drains from the filter pouch into the bottom of the brew basket having an orifice therein such that the fluid extract discharges to a removable container therebelow.
The reservoir is preferably connected to the brew basket for receiving brew water from a spray head of a brewing machine. The reservoir has a plurality of drain holes at a bottom end of the reservoir. The drain holes are located adjacent to flexible fingers extending from the bottom end and contacting an outer surface of the filter pouch to reduce surface tension at the outer surface. The brew water, flowing from the reservoir through the drain holes and over the flexible fingers to the outer surface of the filter pouch, flows primarily into the filter pouch instead of running off the outer surface.
The filter pouch when inclined has the particles accumulate at a bottom end of the filter pouch such that the brew water entering the filter pouch drops onto and infiltrates the particles. The particles are partially fluidized by and suspended in the brew water and they rise with the brew water into an empty portion of the filter pouch preferably without a need for opposing sides of the filter pouch to separate to generate internal space.
Preferably, the filter pouch when inclined provides sufficient exit area that a fluid extract discharge rate matches a rate of brew water entry into the filter pouch when a fluid head is produced inside the filter pouch which is at least as great as a vertical depth of particles in the filter pouch.